Objective: To investigate the effects of mild infections on iron status parameters.
Design: A prospective observational study.
Setting: A population of female nurse students in Norway.
Subjects: 33 women with self-reported episodes of infection and 33 women without infections but with comparable s-ferritin at baseline.
Main outcome measures: Change from baseline in haemoglobin, s-iron, TIBC, transferrin saturation, s-ferritin, e-protoporphyrin and s-transferrin receptor on days 3, 7, 14, 21, 28 and 56 after onset of illness, compared to changes in non-infected subjects tested in parallel.
Results: In febrile illness, such as influenza, there was a significant rise in s-ferritin that could take more than a month to normalise. S-ferritin increased significantly when CRP rose above 20 mg/L, but a normal CRP could not preclude falsely high s-ferritin values due to infection. S-iron and transferrin saturation fell below normal range in a substantial proportion of cases in the symptomatic stage, even in infections without a febrile response, such as the common cold, but was normalised within a week after onset of infection.
Conclusion: For more than a month after febrile illness such as influenza, s-ferritin is not a reliable measure for ruling out iron deficiency in women of reproductive age.